WO2016040560A1

WO2016040560A1 - Methods for the treatment of cancer using gliadin peptides and radiation

Info

Publication number: WO2016040560A1
Application number: PCT/US2015/049316
Authority: WO
Inventors: Fred L. SHAW
Original assignee: Barmarsa Research Llc
Priority date: 2014-09-10
Filing date: 2015-09-10
Publication date: 2016-03-17

Abstract

Methods for treating cancer comprising administration of a therapeutically effective regimen comprising administering a gliadin peptide, radiotherapy, and optionally a chemotherapeutic agent to a patient with cancer are provided. Methods for increasing tumor radiosensitivity and methods for killing chemoresistant and/or radioresistant cancer cells comprising administering an effective amount of a gliadin peptide are also provided.

Description

METHODS FOR THE TREATMENT OF CANCER USING GLIADIN PEPTIDES AND

RADIATION

[0001] This application contains, as a separate part of the disclosure, a sequence listing in computer-readable form (Filename: 48665A_SeqListing.txt; Size: 1,526 bytes; Created:

September 1, 2015) which is incorporated by reference in its entirety.

CROSS-REFERENCE TO RELATED APPLICATION

[0002] This application claims the benefit of priority under 35 U.S.C. § 119(e) of U.S.

Provisional Patent Application No. 62/048,780 filed September 10, 2014, which is incorporated herein by reference.

FIELD OF THE INVENTION

[0003] The invention is directed to methods for treating cancer in a patient comprising administering a gliadin peptide, radiotherapy, and optionally a chemotherapeutic agent. The gliadin peptide may be administered in an amount effective to increase tumor radiosensitivity and to kill radioresistant and/or chemoresistant cancer cells.

BACKGROUND OF THE INVENTION

[0004] With millions of people world-wide dying from cancer each year, there is an ever present need for improved therapeutic options. Cancer treatment can involve a single therapy aimed at reducing tumor size, such as surgery, radiotherapy, or chemotherapy, or a regimen of multiple therapies designed to kill cancer cells and prevent tumor regrowth.

[0005] Cancer resection surgery serves to physically remove a tumor from a patient's body, but a small number of cancer cells can remain following surgery and lead to recurrence of the disease. Radiotherapy, also known as radiation therapy, utilizes the DNA-damaging effects of radiation to kill cancer cells in situ and is used in over half of all cancer patients. In addition to surgery and radiotherapy, a host of chemotherapeutic agents have been developed for use in chemotherapy to combat the various forms of cancer. Examples of classes of chemotherapeutic agents include alkylating agents, antibiotics, antimetabolites, differentiating agents, mitotic inhibitors, steroids, topoisomerase inhibitors, growth factor inhibitors, and tyrosine kinase inhibitors (TKIs). TKIs block the phosphorylation of proteins to inhibit activation of signal transduction pathways that support tumor development and progression. Receptor tyrosine kinase inhibitors (RTKIs) are TKIs that specifically target the activity of receptor tyrosine kinase (RTK) proteins such as epidermal growth factor receptor (EGFR), fibroblast growth factor receptor (FGFR), platelet-derived growth factor receptor (PDGFR), and vascular endothelial growth factor receptor (VEGFR).

[0006] Two RTKIs approved for use in treating cancer are erlotinib (Tarceva®, OSI

Pharmaceuticals) and gefitinib (Iressa®, AstraZeneca). Both drugs target and inhibit EGFR. Activation of EGFR following the binding of epidermal growth factor (EGF) or another ligand to the receptor results in the ATP-driven phosphorylation of tyrosine residues located in the intracellular domain of the receptor. The phosphorylated tyrosines then interact with other intracellular proteins and activate signal transduction pathways to promote cell survival and proliferation. Increased activation of EGFR is associated with a variety of cancer types, especially tumors derived from epithelial cells. The increase in receptor activity can result from mutations in the kinase domain of EGFR, amplification of EGFR gene expression, or

overexpression of the EGFR protein (Yauch et al., Clinical Cancer Research. 2005;11(24):8686- 98). Erlotinib and gefitinib, as well as other RTKIs, interfere with the ATP-binding domain of RTKs to suppress receptor activation and block downstream signal transduction. Erlotinib and gefitinib were the first RTKIs approved for use in treating non- small cell lung cancer (NSCLC). Lung cancer is the leading cause of cancer deaths worldwide, and about 85-90% of lung cancer patients have NSCLC (Gottschling et al. Lung Cancer. 2012; 77(1): 183-91). Patients with certain EGFR mutations have been found to respond better to treatment with RTKIs than those with wild-type EGFR. The prevalence of the mutations is relatively rare, occurring in less than 20% of patients (Yauch 2005, supra).

[0007] Treatment of cancer with a regimen comprising chemotherapy and radiation therapy, also known as chemoradiation or chemoradiotherapy, may increase antitumor effects, but can also result in increased toxicity due to the combined side effects from both the chemotherapy and the radiotherapy. Side effects resulting from chemotherapy and/or radiotherapy include nausea, fatigue, vomiting, diarrhea, tissue damage, fibrosis, infertility, erythema, loss of appetite, gastrointestinal distress or damage, hair loss, bone marrow suppression, dryness, lymphedema, cognitive issues, swelling, skin disorders and inflammation. The presence of EGFR mutations has also been shown to increase the efficacy of combination therapy comprising a RTKI and radiation therapy. In clinical trials of erlotinib and concurrent radiation therapy, patients having brain metastases from NSCLC and EGFR mutations survived for twice as long as patients with wild-type EGFR (Welsh et al., J Clin Oncol. 2013;31(7):895-902). Similarly, combination therapy comprising gefitinib and radiation therapy was markedly more effective at killing cancer cells than radiation or gefitinib treatment alone in lung cancer cells expressing mutant EGFR (Bokobza et al., Int J Radiation Oncol Biol Phys. 2014;88(4):947-954). However, in patients that do not have mutations in the EGFR gene known to increase sensitivity to EGFR inhibitors, co-administration of a RTKI and radiation therapy did not significantly increase cell killing compared to radiation alone (Bokobza et al., supra; Park et al., Mol Cancer. 2010; 9:222).

[0008] The efficacy of anticancer therapy is often hindered by the resistance of cancer cells to radiation (radioresistance) or chemotherapeutic agents (chemoresistance). Radioresistance and chemoresistance refer to the insensitivity of cancer cells to radiation or chemotherapy, respectively, which can be intrinsic or develop over time after repeated exposure to anticancer therapy. For example, the effectiveness of erlotinib and gefitinib in treating NSCLC has been limited, with most patients continuing to exhibit disease progression following initiation of therapy (Witta et al., Cancer Research. 2006; 66(2):944-950). Approximately 70-80% of NSCLC patients with EGFR mutations are sensitive to RTKI therapy, however, virtually all patients eventually acquire resistance (Suda et al. Journal of Thoracic Oncology. 2011; 6(7): 1152-61). Overall, only about 10% of Caucasian NSCLC patients exhibit significant changes in disease progression following therapy with erlotinib or gefitinib (Gottschling 2012, supra). Because cells that are radioresistant and/or chemoresistant can be difficult to kill, they increase the risk of cancer relapse as surviving cells proliferate and lead to tumor regrowth.

[0009] One class of cells exhibiting radioresistance and chemoresistance is cancer stem cells (CSCs) (Chumsri and Shah, Mol Cell Pharmacol. 2013; 5(l):39-49). CSCs are undifferentiated cells that constitute a small subset (typically less than 10%) of cells within a tumor population. CSCs are so named because they possess some of the characteristics of embryonic stem cells and can differentiate into a variety of cancer cell types. CSCs are therefore tumorigenic and can lead to cancer relapse and metastasis, resulting in the overall resistance of the tumor to eradication.

[0010] Gliadin is a protein found in wheat and related grains and is one of the main

components of gluten. The four main types of gliadin are alpha, beta, gamma, and omega.

Gliadin can be digested into a number of active peptides, including some that trigger T-cell immunity or cytotoxicity. Gliadin has been extensively studied for its role in celiac disease, a chronic inflammatory condition related to dietary gluten. Treatment of various cell types, including cancer cells, with gliadin peptides has been demonstrated to activate the EGFR pathway and induce cell proliferation (Barone et al., Gut. 2007; 56(4): 480-488), which strongly suggests that gliadin administration is contraindicated for the treatment of cancer.

SUMMARY OF THE INVENTION

[0011] The invention provides a method of treating cancer comprising administering a therapeutically effective regimen comprising administering a gliadin peptide and radiation therapy to a patient with cancer. The therapeutically effective regimen according to the invention may further comprise administering at least one chemotherapeutic agent to a patient with cancer.

[0012] Thus, the invention also provides a method of treating cancer comprising administering a therapeutically effective regimen comprising administering a gliadin peptide, radiation therapy, and at least one chemotherapeutic agent to a patient with cancer.

[0013] The invention further provides a method of increasing tumor radiosensitivity and/or decreasing radioresistance comprising administering a therapeutically effective amount of a gliadin peptide to a patient with cancer.

[0014] The invention also provides a method of killing a radioresistant and/or chemoresistant cancer cell comprising administering a therapeutically effective amount of a gliadin peptide.

[0015] The gliadin peptide according to the invention may be an alpha-gliadin peptide. Examples of suitable alpha-gliadin peptides include at least alpha-gliadin peptide p31-43, e.g., alpha-gliadin peptide p31-43, alpha-gliadin peptide p31-49, and alpha-gliadin peptide p31-55. When the therapeutically effective regimen according to the invention further comprises administering at least one chemotherapeutic agent, the chemotherapeutic agent may be selected from the group consisting of alkylating agents, antibiotics, antimetabolites, differentiating agents, mitotic inhibitors, steroids, topoisomerase inhibiters, growth factor inhibitors, tyrosine kinase inhibitors, and combinations of the foregoing. In one aspect, the chemotherapeutic agent is a RTKI. A RTKI according the invention may be an EGFR inhibitor. Examples of suitable EGFR inhibitors include gefitinib and erlotinib.

DETAILED DESCRIPTION OF THE INVENTION

[0016] The invention provides methods for treating cancer comprising administering a therapeutically effective regimen, the therapeutically effective regimen comprising administering both a gliadin peptide and radiotherapy to a patient with cancer. In one aspect, the gliadin peptide is administered in an amount effective to decrease the radioresistance and/or increase the radiosensitivity of the cancer. The invention also provides methods of treating cancer comprising administering a therapeutically effective regimen, the therapeutically effective regimen comprising administering each of a gliadin peptide, radiotherapy, and a chemotherapeutic agent to a patient with cancer. In another aspect, the invention provides methods of increasing tumor radiosensitivity and/or decreasing tumor radioresistance comprising administering a therapeutically effective amount of a gliadin peptide to a patient with cancer. In still another aspect, the invention provides methods of killing a radioresistant and/or chemoresistant cancer cell comprising administering a therapeutically effective amount of a gliadin peptide to a patient with cancer.

[0017] As used herein, the following definitions may be useful in aiding the skilled practitioner in understanding the invention:

[0018] The term "regimen" means the use of more than one anticancer therapy selected from the group consisting of surgical resection, administration of a gliadin peptide, radiotherapy, administration of a chemotherapeutic agent, and combinations thereof, to treat cancer in a single patient. A regimen may comprise therapies administered sequentially as monotherapies, e.g., radiotherapy followed by administration of a gliadin peptide, optionally followed by use of a chemotherapeutic agent, or therapies used in combination therapy, e.g., co-administration of radiotherapy and a gliadin peptide. A regimen may also comprise both monotherapy and combination therapy, for example, co-administration of radiotherapy and a gliadin peptide followed by monotherapy with a chemotherapeutic agent, or radiation monotherapy followed by co-administration of a gliadin peptide and a chemotherapeutic agent.

[0019] The term "monotherapy" means that an anticancer therapy selected from the group consisting of administration of a gliadin peptide, radiotherapy, and administration of at least one chemotherapeutic agent, is administered in a manner such that its therapeutic effects on cancer cells and tumors do not overlap with the therapeutic effects of a second anticancer therapy selected from the group consisting of administration of a gliadin peptide, radiotherapy, and administration of at least one chemotherapeutic agent. During monotherapy, a gliadin peptide, radiation, or a chemotherapeutic agent is necessarily administered alone. Gliadin peptide monotherapy may occur before, after, or both before and after, treatment using radiation and/or a chemotherapeutic agent, so long as the radiation and/or chemotherapeutic agent is no longer therapeutically effective at the time the gliadin peptide is administered, i.e., the desired clinical effect(s) of the radiation and/or chemotherapeutic agent are not being achieved at the time the gliadin peptide is administered.

[0020] The terms "co-administering" and "combination therapy" mean that two or more anticancer therapies selected from the group consisting of administration of a gliadin peptide, radiotherapy and administration of at least one chemotherapeutic agent, are administered in a manner that permits the therapies to exert physiological and/or pharmacological effects during an overlapping period of time. In combination therapy comprising a gliadin peptide and at least one chemotherapeutic agent, the gliadin peptide and chemotherapeutic agent(s) may be administered in the same pharmaceutical composition or in separate compositions, via the same or different routes of administration. The anticancer therapies may be co-administered concurrently, i.e., simultaneously, or at different times, as long as the therapies exert physiological and/or pharmacological therapeutic effects during an overlapping period of time. For example, the anticancer therapies may both be administered to a patient within a time period of about 2, 4, 6, 8, 12, 24, or 48 hours. Any of the gliadin peptide, radiotherapy, and chemotherapeutic agent may be administered first. As long as a subsequent therapy is administered while a therapeutic effect of the first therapy is present, the therapies are considered to be co-administered in accordance with the teachings of the invention.

[0021] The term "therapeutically effective" depends on a patient's condition and the specific therapy or therapies administered. The term refers to an amount of a therapy(e.g., a gliadin peptide) or a regimen of therapies (e.g., radiotherapy, a gliadin peptide, and optionally a chemotherapeutic agent) effective to achieve a desired clinical effect. In one aspect, a therapeutically effective regimen refers to the cumulative effect of more than one anticancer therapy selected from the group consisting of administration of a gliadin peptide, radiotherapy and administration of at least one chemotherapeutic agent, e.g., to inhibit growth of cancer cells, prevent metastasis, or result in cancer cell death. In another aspect, a therapeutically effective amount of one or more therapies used in combination therapy, e.g., a gliadin peptide coadministered in combination with another anticancer therapy comprising radiotherapy and/or at least one chemotherapeutic agent, is an amount of the one or more therapies (e.g., gliadin) effective to decrease resistance of a cancer to and/or increase the efficacy of another therapy (e.g., radiotherapy and/or chemotherapy). Dosages and the frequency of administration for use according to the present disclosure may vary according to such factors as the route of administration, the nature and severity of the disease to be treated, and the size and general condition of the patient. Appropriate dosages can be determined by procedures known in the pertinent art, e.g., clinical trials that may involve dose escalation studies and protocols described herein. Generally, a clinician titers the dosage and modifies the route of administration to obtain the optimal therapeutic effect. Some conditions require prolonged treatment to achieve a therapeutic effect; such treatment may or may not entail administering lower doses over multiple administrations. If desired, a dose is administered as two, three, four, five, six or more sub-doses administered separately at appropriate intervals throughout the day. The treatment period will depend on the particular condition and may last one day to several days, weeks, months, or years.

[0022] The term "gliadin peptide" refers to a protein derived from wheat gluten, e.g., bread wheat or durum wheat. The gliadin peptide may be an alpha, beta, gamma, or omega gliadin peptide. In one aspect, the gliadin peptide according to the invention is a derivative or fragment of a gliadin peptide. Examples of suitable gliadin peptides include, but are not limited to, alpha- gliadin peptide p31-55 (LGQQQPFPPQQPYPQPQPFPSQQPY; SEQ ID NO: 1), alpha-gliadin peptide p31-49 (LGQQQPFPPQQPYPQPQPF; SEQ ID NO: 2), alpha-gliadin peptide p31-43 (LGQQQPFPPQQPY; SEQ ID NO: 3), and derivatives or fragments thereof. The term "derivative or fragment" means a peptide having a structure and biological activity similar to a gliadin peptide. A derivative or fragment shares at least 70%, 80%, or 90% amino acid sequence homology with a gliadin peptide. In various embodiments, a derivative or fragment shares at least 70%, 80%, or 90% amino acid sequence homology with alpha-gliadin peptide p31-55, alpha-gliadin peptide p31-49, or alpha-gliadin peptide p31-43. A derivative or fragment may be a chemically modified gliadin peptide. For example, a derivative or fragment can be a gliadin peptide chemically modified to improve the stability, membrane penetration, or immunogenicity of the peptide. Examples of chemical modifications that can be used to form derivatives and fragments of gliadin peptides include, but are not limited to, polymer conjugation (e.g., polyethylene glycol), lipidization, use of amino acid analogs, glycosylation, methylation, and cationization. In one aspect, a suitable derivative or fragment of a gliadin peptide contains at least the amino acid sequence PPQQPY (SEQ ID NO: 4).

[0023] The term "radiation therapy" or "radiotherapy" refers to the use of radiation to damage and ultimately kill cancer cells and reduce tumor size. Radiotherapy may be delivered from an source outside the body (external beam radiotherapy) or from an internal source placed in the body (internal radiotherapy/brachiotherapy). Examples of radiation therapy contemplated for use according to the invention include, but are not limited to, gamma rays, X-rays, microwaves, ultraviolet radiation, directed delivery of radioisotopes to tumors, and combinations thereof.

[0024] The terms "radiosensitivity" and "radioresistance" relate to the efficacy of radiotherapy in treating a given cancer. Radiosensitivity refers to the susceptibility of a cancer cell to the toxic effects of radiotherapy. Radioresistance refers to the ability of a cancer cell to avoid the damaging effects of radiotherapy. Changes in radiosensitivity and radioresistance can be measured by comparing the toxic effects of radiotherapy to cancer cells after a single treatment, e.g., in different patients, or by assessing changes in toxicity to cancer cells over the course of repeated treatments, e.g., in the same patient or different patients. An increase in radiosensitivity or decrease in radioresistance of a cancer cell means an improvement in the therapeutic efficacy of radiotherapy.

[0025] The term "chemotherapeutic agent" means any compound that is toxic with respect to cancer cells. A chemotherapeutic agent can be a small molecule, protein, polypeptide, peptide, nucleic acid, and combinations thereof. Examples of classes of chemotherapeutic agents include alkylating agents, antibiotics, antimetabolites, differentiating agents, mitotic inhibitors, steroids, topoisomerase inhibitors, growth factor inhibitors, and TKIs. Specific examples of chemotherapeutic agents include, but are not limited to, azacitidine, axathioprine, bevacizumab, bleomycin, capecitabine, carboplatin, chlorabucil, cisplatin, cyclophosphamide, cytarabine, daunorubicin, docetaxel, doxifluridine, doxorubicin, epirubicin, etoposide, fluorouracil, gemcitabine, herceptin, idarubicin, mechlorethamine, melphalan, mercaptopurine, methotrexate, mitoxantrone, oxaliplatin, paclitaxel, tafluposide, teniposide, tioguanine, retinoic acid, valrubicin, vinblastine, vincristine, vindesine, vinorelbine, the specific exemplary RTKIs listed herein, and combinations thereof. Additional examples of chemotherapeutic agents are known in the art.

[0026] The term "receptor tyrosine kinase inhibitor" or "RTKI" means any compound capable of inhibiting the activity of a member of the receptor tyrosine kinase (RTK) family of proteins. A RTKI can be a small molecule, protein, polypeptide, peptide, nucleic acid, and combinations thereof. Examples of protein targets for RTKIs include, but are not limited to, members of the following RTK families: ephrin receptor, epidermal growth factor receptor, fibroblast growth factor receptor, insulin receptor, insulin-like growth factor receptor, neutrophin receptors, platelet-derived growth factor receptor, and vascular endothelial growth factor receptor. Specific exemplary RTKIs are listed below.

[0027] The terms "chemosensitivity" and "chemoresistance" relate to the efficacy of a chemotherapeutic agent in treating cancer. Chemosensitivity refers to the susceptibility of a cancer cell to the cytotoxic effects of a chemotherapeutic agent. Chemoresistance refers to the ability of a cancer cell to avoid the intended therapeutic cytotoxic effects of a chemotherapeutic agent. Changes in chemosensitivity and chemoresistance can be measured by comparing the toxic effects of chemotherapy after a single treatment (e.g., in different patients) or by assessing changes in toxicity over the course of repeated treatments (e.g. in the same patient or different patients). An increase in chemosensitivity or decrease in chemoresistance of a cancer cell means an improvement in the therapeutic efficacy of a chemotherapeutic agent.

[0028] In one aspect, the invention provides a method of treating cancer comprising administering a therapeutically effective regimen comprising administering a gliadin peptide and radiation therapy to a patient with cancer. In one aspect, the radiotherapy is administered first as monotherapy, followed by gliadin peptide monotherapy. In another aspect, the gliadin peptide monotherapy is administered first, followed by radiotherapy. In another aspect, the radiotherapy and a gliadin peptide are co-administered as combination therapy. In one aspect of combination therapy, the radiotherapy and gliadin peptide are administered concurrently, i.e., simultaneously. For example, a gliadin peptide may be administered, for example, via infusion, to a patient at the same time said patient is receiving a dose of radiation. In another aspect of combination therapy, the gliadin peptide is administered before radiotherapy, for example, 1 hour, 2 hours, 4 hours, 6 hours, 8 hours, 12 hours, 24 hours, 48 hours, or 72 hours before administration of a dose of radiation. In another aspect of combination therapy, the radiotherapy is administered before the gliadin peptide. Because radiotherapy can damage cellular DNA in a manner that prevents growth and ultimately results in cell death, the desired clinical effects of radiotherapy can persist for an extended period of time following administration of a dose or multiple doses of radiation. The radiation and gliadin peptide may therefore be co-administered to a patient within a time period of about 2, 4, 6, 8, 12, or 24 hours; about 2, 3, 4, 5, 6, or 7 days; about 2, 3 or 4 weeks; or about 2, 3, 4, 5, 6, or more, months.

[0029] In one aspect, a method of treating cancer comprising administering a therapeutically effective regimen according to the present disclosure comprises administering a gliadin peptide in an amount effective to decrease the radioresistance and/or increase the radiosensitivity of the cancer. The present disclosure also provides a method of increasing tumor radiosensitivity in a patient and/or decreasing tumor radiosensitivity comprising administering a therapeutically effective amount of a gliadin peptide to a patient with cancer who has received, will receive, or is currently receiving, radiotherapy. For example, the gliadin peptide may be administered in an amount effective to increase tumor radiosensitivity by increasing the number of cancer cells killed following a radiotherapy session or course of radiotherapy compared to when no gliadin peptide is administered, e.g., in the same patient or different patients. In such a manner, administration of a gliadin peptide may allow for a smaller dose of radiation to be administered without reducing the toxic effects to cancer cells, thereby minimizing the potential damage to healthy cells. A gliadin peptide may also be administered to prevent or delay the onset of radioresistance, to prolong the anticancer effects of radiotherapy.

[0030] In one aspect, a method of treating cancer comprising administering a therapeutically effective regimen comprising a gliadin peptide and radiotherapy according to the present disclosure further provides administering at least one chemotherapeutic agent. In another aspect, the invention provides a method of treating cancer comprising administering a therapeutically effective regimen comprising administering a gliadin peptide, radiation therapy, and at least one chemotherapeutic agent to a patient with cancer. In one aspect, the therapies are administered in any order as sequential monotherapies, for example, radiotherapy followed by administration of a gliadin peptide, followed by administration of a chemotherapeutic agent. In another aspect, either the gliadin peptide, radiation therapy, or chemotherapeutic agent is administered first as monotherapy, and the other two therapies are co-administered as combination therapy, for example, radiotherapy followed by combination therapy comprising a gliadin peptide and a chemotherapeutic agent. In still another aspect, two therapies, e.g., radiotherapy and a gliadin peptide, or a gliadin peptide and a chemotherapeutic agent, are co-administered as combination therapy first, followed by the third therapy administered as monotherapy. In one aspect, the gliadin peptide, radiation therapy, and chemotherapeutic agent are co-administered as combination therapy. In one aspect of combination therapy, the gliadin peptide, radiation therapy, and chemotherapeutic agent are administered concurrently. In another aspect of combination therapy, either the gliadin peptide, radiation therapy, or chemotherapeutic agent is administered first, and the other two therapies are administered concurrently while the physiological and/or pharmacological effects of the first therapy persist, for example, radiotherapy is administered to a patient first, followed by concurrent administration of a gliadin peptide and a chemotherapeutic agent. In still another aspect of combination therapy, two therapies, e.g., radiotherapy and a gliadin peptide, or a gliadin peptide and a chemotherapeutic agent, are administered concurrently, followed by the third therapy. In another aspect of combination therapy, the three therapies are administered in any order, but not concurrently.

[0031] In one aspect, the gliadin peptide and radiotherapy are administered in an amount effective to decrease the chemoresistance and/or increase the chemosensitivity of the cancer to the chemotherapeutic agent. In one aspect, the gliadin peptide is administered in an amount effective to increase tumor chemosensitivity by increasing the number of cancer cells killed following administration of a chemotherapeutic agent compared to when no gliadin peptide is administered, e.g., in the same patient or different patients. In such a manner, administration of a gliadin peptide may allow for a smaller dose of a chemotherapeutic agent to be administered without reducing the toxic effects to cancer cells, thereby minimizing the side effects of the chemotherapeutic agent. In another aspect, a gliadin peptide is administered to prevent or delay the onset of tumor chemoresistance, to prolong the anticancer effects of the chemotherapeutic agent.

[0032] In one aspect, the therapeutically effective regimen comprising administering a gliadin peptide and radiotherapy, or a gliadin peptide, radiotherapy, and a chemotherapeutic agent, is administered to a patient that has previously had cancer resection surgery. When administered following cancer resection surgery to physically remove cancer cells and decrease tumor size, the methods of the present disclosure can be used to kill surviving cancer cells and prevent tumor regrowth and cancer relapse.

[0033] In various aspects, the methods of the present disclosure comprise administering a gliadin peptide, radiotherapy, and/or a chemotherapeutic agent. The gliadin peptide may be an alpha, beta, gamma, or omega gliadin peptide. In one aspect, the gliadin peptide according to the invention is an alpha-gliadin peptide or a derivative or fragment thereof. Examples of suitable alpha-gliadin peptides include at least alpha-gliadin peptide p31-43, e.g., alpha-gliadin peptide p31-55 (SEQ ID NO: 1), alpha-gliadin peptide p31-49 (SEQ ID NO: 2), and alpha-gliadin peptide p31-43 (SEQ ID NO: 3). In a preferred embodiment, the alpha-gliadin peptide is alpha- gliadin peptide p31-43 or p31-55 or a derivative or fragment thereof. Alpha-gliadin peptide p31- 43 has the amino acid sequence LGQQQPFPPQQPY (SEQ ID NO:3) and is often referred to as the "toxic" gliadin peptide because it induces an innate inflammatory immune response and results in intestinal damage. Alpha- gliadin peptide p31-55 has the amino acid sequence LGQQQPFPPQQPYPQPQPFPSQQPY (SEQ ID NO: 1) and is resistant to digestion in the gastrointestinal tract and exhibits permeability across a model of the gut epithelium (lacomino et al, JAgric Food Chem. 2013; 61(5): 1088-96).

[0034] A gliadin peptide according to the invention may be obtained following enzymatic digestion of a gliadin protein or can be chemically synthesized using conventional methods known in the art. For a gliadin peptide, a therapeutically effective amount used alone or as part of a regimen according to the invention is generally a dosage necessary to achieve a plasma concentration of about 5 μg/mL to about 200 μg/mL, about 10 μg/mL to about 100 μg/mL, and/or about 15 μg/mL to about 50 μg/mL, for example, about 20 μg/mL. Purely by way of illustration, the dosage of a gliadin peptide needed to achieve a therapeutically effective amount alone or as part of a regimen ranges from about 100 μg/kg/day to about 100 mg/kg/day, about 200 μg/kg/day to about 75 mg/kg/day, about 500 μg/kg/day to about 50 mg/kg/day, about 750 μg /kg/day to about 25 mg/kg/day, and/or about 1 mg/kg/day to about 15 mg/kg/day, depending on the factors mentioned above. Consistent therewith, a therapeutically effective regimen according to the invention comprises a gliadin peptide administered in a dosage of at least 100 μg/kg/day and/or in an amount effective to achieve a plasma concentration of the gliadin peptide of about 5 μg/mL. A pharmaceutical composition comprising a gliadin peptide comprises the peptide in combination with a pharmaceutically acceptable carrier, diluent, and/or excipient(s). Routes of administration suitable for administering a pharmaceutical composition comprising gliadin to a patient include, but are not limited to, enteral (i.e., oral) and parenteral (e.g., intramuscular, intravenous, respiratory/inhalation, and subcutaneous). In one aspect, the gliadin peptide is administered parenterally. U.S. Patent Application Serial No. 14/200,585, incorporated herein by reference, teaches the administration of gliadin peptide alone or in combination with a chemotherapeutic agent, for the treatment of cancer.

[0035] Types of radiotherapy for use according to the present disclosure include, but are not limited to, intensity-modulated radiation therapy (IMRT), image-guided radiation therapy (IGRT), tomotherapy, three-dimensional conformal radiation therapy (3DCRT), sterotactic radiosurgery (SRS), sterotactic body radiation therapy (SBRT), particle therapy (e.g., proton therapy, electron therapy, boron therapy, neon therapy), augur therapy, intraoperative radiation therapy (IORT), interstitial brachytherapy, intracavity brachytherapy, episcleral brachytherapy, permanent brachytherapy, temporary brachytherapy, total body irradiation, systemic radiation therapy, and combinations thereof. The frequency and duration of radiation therapy varies and can range from 1, 2, 3, or more, times a day/week/month over the course of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or more, days or weeks. The radiation dosage depends on a number of factors including the radiation source, cancer type, size and/or location of the cancer, health of the patient, and other anticancer therapies administered. Radioisotopes for use in radiotherapy include, but are not limited to, radioactive forms of astatine, carbon, chrominum, chlorine, iron, cobalt, copper, europium, gallium, hydrogen, iodine, indium, lutetium, phosphorus, rhenium, samarium, selenium, strontium, sulphur, technicium, yttrium, and combination thereof. Radiotherapy according to the invention may be measured in Gray units (Gy) and administered in a range of 1 Gy to 100 Gy administered in a single dose or series of doses, for example, about 60 Gy to about 80 Gy, about 40 Gy to about 60 Gy, about 20 Gy to about 40 Gy, optionally administered in dose fractions of about 1 Gy to about 5 Gy per day.

[0036] Examples of chemotherapeutic agents that may be administered according to the present disclosure include, but are not limited to, alkylating agents, antibiotics, antimetabolites, differentiating agents, mitotic inhibitors, steroids, topoisomerase inhibitors, growth factor inhibitors, TKIs (such as RTKIs), and combinations thereof. Specific chemotherapeutic agents contemplated for use according to the invention include, but are not limited to, azacitidine, axathioprine, bevacizumab, bleomycin, capecitabine, carboplatin, chlorabucil, cisplatin, cyclophosphamide, cytarabine, daunorubicin, docetaxel, doxifluridine, doxorubicin, epirubicin, etoposide, fluorouracil, gemcitabine, herceptin, idarubicin, mechlorethamine, melphalan, mercaptopurine, methotrexate, mitoxantrone, oxaliplatin, paclitaxel, tafluposide, teniposide, tioguanine, retinoic acid, valrubicin, vinblastine, vincristine, vindesine, vinorelbine, the specific exemplary RTKIs listed below, and combinations thereof. Chemotherapeutic agents for use in the invention can be administered according to treatment schedules typically determined by a healthcare provider. [0037] In one aspect, the chemotherapeutic agent is a RTKI. Examples of RTKIs include, but are not limited to, afatinib, axitinib, canertinib, cediranib, erlotinib, gefitinib, grandinin, imatinib, lapatinib, leflunomide, lestaurtinib, neratinib, pazopanib, quizartinib, regorafenib, semaxanib, sorafenib, sunitib, sutent, tivozanib, tocerabib, vandetanib, vatalanib, monoclonal antibodies that bind specific RTKs, and combinations thereof. A preferred RTKI according to the invention is an inhibitor of EGFR. Examples of EGFR inhibitors include, but are not limited to, gefitinib and erlotinib. Therapeutically effective amounts of known chemotherapeutic agents are known in the art. For example, a therapeutically effective amount of a RTKI is generally about 5 mg/kg/day to about 150 mg/kg/day, about 10 mg/kg/day to about 100 mg/kg/day, and/or about 25 mg/kg/day to about 75 mg/kg/day, depending on the drug. Thus, exemplary amounts of a chemotherapeutic agent that can be used in a therapeutically effective regimen according to the invention may be about 5 mg/kg/day to about 150 mg/kg/day, about 10 mg/kg/day to about 100 mg/kg/day, and/or about 25 mg/kg/day to about 75 mg/kg/day.

[0038] The methods disclosed herein can be used to treat a human patient with cancer or any other mammal. The invention is useful for treating many types of cancer including bladder cancer, breast cancer, colon cancer, endometrial cancer, kidney cancer, leukemia, lung cancer, lymphoma, pancreatic cancer, prostate cancer, skin cancer, brain cancer, thyroid cancer, and metastatic forms thereof. In one aspect, the invention is used to treat lung cancer, including NSCLC.

[0039] Advantageously, a method of treating cancer comprising administering a therapeutically effective regimen of a gliadin peptide, radiotherapy, and optionally a chemotherapeutic agent is effective to decrease or prevent resistance of the cancer cells to the radiotherapy and/or chemotherapeutic agent. The administration of a therapeutically effective regimen according to the present disclosure, therefore, increases and prolongs the efficacy of radiotherapy and/or chemotherapy. While not intending to be bound by a single theory, it is believed that the anticancer effect achieved from administering a gliadin peptide as part of a regimen comprising radiotherapy and/or at least one chemotherapeutic agent according to the invention can be attributed to the impact of the gliadin peptide on the intracellular transport of cargo, including chemotherapeutic agents and EGFR. [0040] Proteins, chemotherapeutic agents, and other molecules are trafficked within the cytosolic compartment of cells in vesicles known as endosomes as part of the endocytic pathway. Early endosomes are vesicles that receive molecules internalized from the plasma membrane. Early endosomes mature into late endosomes, also known as multivesicular bodies (MVBs). The late endosomes/MVBs eventually fuse with lysosomes, resulting in the enzymatic degradation of the internalized cargo. As an alternative to lysosomal degradation, some molecules are sorted into recycling endosomes and trafficked back to the plasma membrane or to other intracellular sites. Gliadin peptides, particularly alpha-gliadin peptide p31-43, have been shown to interfere with the endocytic pathway by delaying maturation of early endosomes to late endosomes (Barone 2010, supra). As a result, lysosomal degradation does not readily occur and gliadin peptides can interfere with the degradation of proteins, chemotherapeutic agents, and other molecules trafficked within endosomes in the cytosolic compartment, leading to increased concentrations of chemotherapeutic agents and proteins that promote the sensitivity of the cell to chemotherapeutic agents, advantageously resulting in increased cytotoxicity.

[0041] The endosomal sorting complex required for transport (ESCRT) protein complexes (ESCRT-0, ESCRT- 1, ESCRT-2, and ESCRT-3) regulate the sorting of cargo into MVBs for eventual degradation within lysosomes. Hepatocyte growth factor-regulated tyrosine kinase substrate (HRS), a component of ESCRT-0, regulates the trafficking of molecules in early and late endosomes (Henne et al. Developmental Cell. 2011; 21(1):77— 91; Barone 2010, supra). Amino acids 719-731 of HRS, located at the carboxyl terminus, contain the binding domains necessary for the localization of HRS to endosomal membranes (Barone 2010, supra). The sequence of HRS amino acids 719-731 (PSQDASLPPQQPY; SEQ ID NO:5) is very similar to the alpha-gliadin peptide p31-43 peptide. Out of 13 residues, seven are identical, including six contiguous amino acids (PPQQPY; SEQ ID NO:4), and two are similar between the sequences, with the only significant difference being an N-terminal leucine in alpha-gliadin peptide p31-43 compared to the proline in HRS 719-731 (Barone 2010, supra). Alpha-gliadin peptides comprising at least alpha-gliadin p31-43, e.g., alpha-gliadin peptide p31-43, alpha-gliadin peptide p31-49, and alpha-gliadin peptide p31-55, can therefore compete with HRS binding, thereby interfering with HRS localization within endosomal membranes (Barone 2010, supra). As a result, after cells are treated with alpha-gliadin peptides comprising at least alpha-gliadin peptide p31-43, the amount of HRS in the cytosol is increased while membrane- associated HRS is decreased (Barone 2010, supra). The decreased presence of HRS associated with the endosomal membranes disrupts the normal trafficking of cargo within the cell, leading to impaired degradation and thus prolonged retention of intracellular molecules including chemotherapeutic agents and proteins that promote the sensitivity of the cell to chemotherapeutic agents, advantageously resulting in increased cytotoxicity.

[0042] After out-competing HRS for binding sites associated with endosomal membranes, alpha-gliadin peptides comprising at least alpha-gliadin p31-43, e.g., alpha-gliadin peptide p31- 43, alpha-gliadin peptide p31-49 and alpha-gliadin peptide p31-55, are localized to endosomes. Vesicles carrying alpha-gliadin peptides comprising at least alpha-gliadin peptide p31-43 move more slowly than normal vesicles (Barone 2010, supra). The delay of intracellular transport induced by alpha-gliadin peptide p31-43 is not influenced by the cargo within the vesicles, so all molecules trafficked intracellularly, including growth factor receptors and chemotherapeutic agents, are potentially affected (Barone 2010, supra).

[0043] The disruption in intracellular trafficking of proteins following administration of a gliadin peptide may make radiation more effective. EGFR is an important determinant of radiosensitivity because after cells are exposed to radiation, EGFR translocates to the nucleus and binds to DNA-dependent protein kinase (DNA-PK) to aid in DNA repair. Mutations in EGFR that interfere with the translocation of EGFR to the nucleus eliminate EGFR-mediated radioprotection (Das et al., Cancer Research. 2007; 67(l l):5267-5274). Because administration of a gliadin peptide blocks the trafficking of EGFR to the nucleus, the gliadin peptide can interfere with DNA repair and advantageously increase the sensitivity of cancer cells to radiation.

[0044] In preventing the degradation of intracellular molecules, gliadin peptides can also enhance the anticancer activity of chemotherapeutic agents. The prolonged cytosolic transit of cargo can extend the time in which a chemotherapeutic agent is able to accumulate, leading to higher intracellular concentrations of drug and increased cytotoxicity. The extended presence of the drug within the cell also allows the drug to exert its pharmacological effect within a cell for a longer period of time, enhancing the drug's efficacy. A regimen comprising administration of a gliadin peptide can therefore potentiate both the activity of radiotherapy and a wide range of anticancer drugs having various mechanisms of action to treat a range of cancer types.

[0045] The effect of gliadin peptides on the endocytic pathway can also achieve anticancer therapeutic effects by influencing cellular phenotype. Epithelial and mesenchymal are two main classes of cellular phenotypes. Epithelial cells are highly organized, with numerous cell junctions maintaining adherence between neighboring cells. In contrast, mesenchymal cells are disorganized and lack strong intercellular junctions, which increases their migratory potential. During a process known as the mesenchymal transition (MT), epithelial cells and non-epithelial cells differentiate into mesenchymal cells. The transition results in the loss of cell-cell adhesion and increased cell motility, as well as increased resistance to apoptosis, thereby promoting the invasiveness, i.e., metastasis, of tumors. During MT, expression of cell junction proteins such as e-cadherin is decreased, and expression of mesenchymal markers such as vimentin and fibronectin increases. Radiotherapy has been shown to promote MT (Zhou et al., Int J Radiat Oncol Biol Phys. 2011; 81: 1530-1537).

[0046] Low expression of e-cadherin has been associated with the progression of a number of cancer types (Rao et al. Cell Biol. Int. 2011; 35(9):945-51; Yilmaz et al. Molecular Cancer Research. 2010; l;8(5):629-42). Administration of a gliadin peptide can prevent a mesenchymal phenotype by impairing e-cadherin degradation , allowing for continued cell-to-cell adhesion. The effect of gliadin on e-cadherin retention may explain why the presence of plasma gliadin leads to reduced enterocyte height and villous atrophy in untreated celiac patients (Barone 2010, supra) because changes in cellular adhesion through the loss of e-cadherin are necessary to promote vertical growth of intestinal cells. Additionally, by interfering with HRS and the ESCRT complexes, gliadin peptides can prevent the degradation of focal adhesions that connect cells to the extracellular matrix (Tu et al. Proceedings of the National Academy of Sciences. 2010; 107(37): 16107-12). The intact focal adhesions also help maintain the non-mesenchymal phenotype and inhibit transition to a mesenchymal state. Because administration of a gliadin peptide according to the invention can block MT, counteracting the effects of radiotherapy on promoting MT, to prevent cell growth and cellular migration (and thus metastasis of cancer cells), the treatment according to the invention can effectively control a spectrum of cancer types.

[0047] The effect of gliadin peptides on MT can also increase the efficacy of radiotherapy and chemotherapy. Loss of e-cadherin associated with MT promotes radioresistance in tumor cells (Theys et al., Radiother Oncol. 2011 Jun;99(3):392-7). A mesenchymal phenotype has also been identified as predictive of drug sensitivity, with expression of mesenchymal markers signaling a poor response to chemotherapy (Yauch 2005, supra; Buck et al. Molecular Cancer Therapeutics. 2007; 6(2):532-41; Frederick et al. Molecular Cancer Therapeutics. 2007; 6(6): 1683-1691). E- cadherin expression is substantially absent in resistant cancer cell lines, and restoration of e- cadherin expression can increase drug sensitivity, resulting in cell growth inhibition and apoptosis following treatment (Witta 2006, supra). The administration of gliadin peptides to promote retention of e-cadherin and a non-mesenchymal phenotype can therefore improve the response of cancer cells to radiotherapy and/or a chemotherapeutic agent. For example, a mesenchymal phenotype is associated with lower amounts of e-cadherin and with both intrinsic and acquired resistance to EGFR-specific RTKIs in NSCLC (Suda 2011, supra). Non- mesenchymal cells rely on EGFR-mediated pathways for cell survival and proliferation, but in the mesenchymal state, EGFR signaling is reduced and cells are believed to rely on EGFR- independent mechanisms for cell survival and proliferation (Thomson et al. Clin. Exp. Metastasis. 2008; 25(8):843-54). Use of a gliadin peptide to maintain e-cadherin and prevent transition to a mesenchymal state will therefore decrease drug resistance and prolong the sensitivity of cancer calls to the cytotoxic effects of an EGFR-specific RTKI such as gefitinib or erlotinib. Administration of a gliadin peptide is expected to act synergistically with other classes of chemotherapeutic agents as well, resulting in improved options for therapeutically effective regimens to treat cancer.

[0048] The ability of a gliadin peptide to increase the therapeutic efficacy of another anticancer therapy may also be attributable in part to the interaction of the gliadin peptide with proteins important for maintaining genome stability. In addition to HRS, the alpha gliadin peptide p31-43 shares the six amino acid sequence PPQQPY (SEQ ID NO: 4) with residues found within the kinase domain of cyclin-dependent kinase 12 (CDK12). The kinase domain of CDK12 is important for its interaction with cyclin K (CycK) (Dai et al., J. Biol. Chem. 2012; 287(30):25344-52). The CycK-CDK-12 complex is important for the cellular response to DNA damage, and loss of the complex increases a cell's sensitivity to DNA-damaging agents (Blazek et al., Genes Dev. 2011 Oct 15;25(20):2158-72). Based on the foregoing and the results shown in the Examples below, alpha- gliadin peptides comprising at least alpha-gliadin peptide p31-43 can interfere with the interaction between CDK12 and CycK and inhibit the activity of the two proteins, thereby increasing the sensitivity of the tumor to the DNA damage induced by radiotherapy and/or a chemotherapeutic agent.

[0049] The therapeutic efficacy achievable from administering a gliadin peptide and at least one chemotherapeutic agent to treat cancer is surprising and unexpected considering the characterization of the activity of the compounds as being contrary. For example, gliadin peptides are known to drive cells into S-phase of the cell cycle, thereby promoting cell proliferation (Barone 2007, supra), while chemotherapeutic agents generally are cytotoxic, particularly to rapidly dividing cells. RTKIs such as erlotinib and gefitinib generally act to arrest cells in Gl-phase to inhibit cell growth (Arora et al., JPET. 2005;315(3):971-79). Thus, the activity of a gliadin peptide and chemotherapeutic agent would be expected to at least partially counteract each other. Similarly, the activity of an EGFR activator such as a gliadin peptide and an EGFR inhibitor such as a RTKI would be expected to be contrary to each other. However, because gliadin peptides also cause EGFR and other receptors to be recycled back to the cell membrane instead of degraded within lysosomes, the time during which EGFR remains phosphorylated, i.e., activated, is extended (Barone 2007, supra; Barone 2010, supra). Such a prolonged activation of EGFR and other RTKs following administration of a gliadin peptide is similar to the constitutive activation of EGFR in cancer cells carrying a EGFR mutation associated with increased sensitivity to a RTKI (Okabe et al., Cancer Res. 2007; 67(5): 2046- 2053). Administration of a gliadin peptide may thus reduce resistance to a RTKI. The administration of a gliadin peptide and an EGFR- specific RTKI as part of a regimen according to the present disclosure is therefore effective for treating patients with wild-type EGFR and those expressing mutant receptor proteins. [0050] The anticancer effect achieved from administering a gliadin peptide alone or as part of a therapeutically effective regimen according to the invention may thus also be attributed to the unexpected advantageous effect of the gliadin peptide on resistant cells. In one aspect, the invention provides a method of killing a chemoresistant and/or radioresistant cell comprising administering an effective amount of a gliadin peptide to a patient having cancer. In one aspect, the patient has previously received radiotherapy and/or chemotherapy. Because gliadin peptides are surprisingly effective at killing cells that are resistant to other chemotherapeutic agents, such as undifferentiated cells including CSCs, they serve as an effective anticancer therapy when used in a regimen following an anticancer therapy such as radiotherapy or chemotherapy that is no longer therapeutically effective.

[0051] The therapeutic effect of a gliadin peptide administered as part of a therapeutically effective regimen according to the invention that includes administration of a chemotherapeutic agent may be affected by the mechanism of action of the chemotherapeutic agent. In particular, administration of a gliadin peptide following a chemotherapeutic agent whose main site of action is in the nucleus, e.g., alkylating agents, antibiotics, topoisomerase inhibitors, and other agents that damage DNA, has been found to be surprisingly effective at inhibiting resistant cancer cells that survive treatment with the chemotherapeutic agent, particularly relative to concurrent coadministration of both compounds. For such chemotherapeutic agents and for any chemotherapeutic agent that is dependent on the endocytic pathway to reach its site of action, the methods of the present disclosure comprise, in one aspect, administering a gliadin peptide in such a manner, e.g., gliadin peptide monotherapy before or after administration of the chemotherapeutic agent, so as to prevent interference with the localization of the chemotherapeutic agent to its site of action. For chemotherapeutic agents whose primary site of action is outside the nucleus (e.g., in the cytosol or in another organelle) or that do not depend on the endocytic pathway for intracellular targeting e.g., differentiating agents, mitotic inhibitors, steroids, and TKIs, a regimen comprising administration of a gliadin peptide and the chemotherapeutic agent is surprisingly effective at inhibiting cancer cell growth and can surprisingly achieve synergistic therapeutic efficacy greater than monotherapy with the gliadin peptide or chemotherapeutic agent alone. The administration of a gliadin peptide before and/or after treatment with at least one chemotherapeutic (e.g., monotherapy when the compounds do not exert pharmacological effects during an overlapping period of time) or during administration of at least one chemotherapeutic (i.e, co-administration when the compounds do exert pharmacological effects during an overlapping period of time) is therefore effective to decrease the number of resistant cells such as CSCs and prevent cancer relapse and metastasis.

[0052] A regimen comprising a gliadin peptide, radiotherapy, and optionally a chemotherapeutic agent provides an unexpected and surprisingly effective anticancer therapy. The gliadin peptide acts in concert with the radiotherapy and/or chemotherapeutic agent(s) to achieve enhanced therapeutic efficacy. A patient suffering from both untreated celiac disease and cancer could be expected to respond well to a therapeutic regimen according to the present disclosure. Celiac disease is a chronic inflammatory disease of the small intestine that involves an immunogenic response to wheat gluten and similar proteins. Adopting a gluten-free diet mitigates the symptoms of celiac disease. In patients suffering from untreated celiac disease, gliadin peptides are resistant to degradation and transported intact into serum in significantly higher amounts compared to healthy subjects and patients with treated celiac disease (Matysiak- Budnik et al. Gastroenterology . 2003;125(3):696-707), creating a condition known as "leaky gut syndrome." The increased permeability of gliadin through the lining of the digestive track and into systemic circulation would allow gliadin peptides to reach tumor sites and increase the sensitivity of the cancer cells to radiotherapy and/or chemotherapy. Thus, according to one aspect, the patient to be treated is not suffering from untreated celiac disease.

[0053] The invention is further explained by the following Examples which should not be construed as limiting its scope.

Example 1

[0054] For Examples 1 to 4, human cancer cell lines A549, NCI-H1975, and PANC-1 were obtained from ATCC and maintained in RPMI 1640 media (Life Technologies, Inc., Grand Island, NY) containing 10% fetal bovine serum, 2 mM L-glutamine and 1% antibiotic- antimycotic solution (10 units^L penicillin, 10 μg/μL streptomycin and 25 μg/mL amphotericin B). Cells were kept at 37 °C in a humidified atmosphere of 5% C0₂ and grown until they reached a confhiency of 90%. Cells were then washed, trypsinized, and counted using a Coulter counter (Beckman, Brea, CA).

[0055] A549 NSCLC cells were maintained and cultured as described above. Alpha-gliadin peptide p31-43 (Anaspec Inc., Fremont, CA), gefitinib (LC Laboratories, Woburn, MA), and erlotinib (LC Laboratories) were used to treat the cells. Cells were plated at a density of 10,000 cells/well in 24- well cell culture plates and allowed to adhere for 24 hours. The cells were then incubated for 72 hours with the following: (1) vehicle (DMSO/water); (2) 5 μg/mL, 20 μg/mL, or 70 μg/mL alpha-gliadin peptide p31-43; (3) 1 μΜ gefitinib in DMSO/water; (4) 1 μΜ erlotinib; (5) 5 μg/mL, 20 μg/mL, or 70 μg/mL alpha-gliadin peptide p31-43 and 1 μΜ gefitinib in DMSO/water; or (6) 5 μg/mL, 20 μg/mL, or 70 μg/mL alpha-gliadin peptide p31-43 and 1 μΜ erlotinib in DMSO/water. All experiments were conducted in sextuplicate. For combination therapy using alpha-gliadin peptide p31-43 and gefitinib/erlotinib, the two compounds were administered to the cells simultaneously. Following 72 hours of treatment, growth inhibition was evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay (Roche Diagnostics Corporation, Indianapolis, IN) according to the manufacturer's instructions. The absorbance at 570 nm was measured using a plate reader (BioTek, Winooski, VT). Table 1 shows the mean absorbance at 570 nm and the percent growth inhibition for gliadin- and RTKI- treated A549 cells compared to vehicle-treated cells.

Table 1: Effects of alpha-gliadin peptide p31-43 alone or in combination with gefitinib or erlotinib on A549 cell proliferation following 72-hour treatment

+ 1 μg/mL erlotinib

70 μg/mL gliadin 0.86 0.04 42.3 p < 0.05

+ 1 μg/mL erlotinib

5 μg/mL gliadin + 1.24 0.04 16.8 p > 0.05

1 μg/mL gefitinib

20 μg/mL gliadin 1.14 0.02 23.5 p > 0.05

+ 1 μg/mL gefitinib

70 μg/mL gliadin 1.30 0.16 12.8 p > 0.05

+ 1 μg/mL gefitinib

[0056] A549 cells treated with alpha-gliadin peptide p31-43 alone at a dose of 20 μg/mL or 70 μg/mL exhibited comparable growth inhibition compared to cells treated with gefitinib or erlotinib alone. Treatment with a combination of alpha-gliadin peptide p31-43 and gefitinib or erlotinib resulted in increased growth inhibition compared to alpha-gliadin peptide p31-43 or each RTKI alone. Co-administration of alpha-gliadin peptide p31-43 and gefitinib or erlotinib surprisingly had a synergistic effect on growth inhibition, with the combination therapy resulting in greater growth inhibition than the sum of the individual growth inhibitory effects of the alpha- gliadin peptide p31-43 and the RTKI.

[0057] Overall, the results demonstrated that a gliadin peptide administered alone was an effective anticancer treatment and inhibited cancer cell growth as well as a benchmark chemotherapeutic agent. Combination therapy using a gliadin peptide and a RTKI

advantageously resulted in increased inhibition of cancer cell growth compared to either the gliadin peptide or RTKI alone and also produced a surprising and unexpected synergistic antitumor effect.

Example 2

[0058] NCTH1975 NSCLC cells were maintained and cultured as described in Example 1. NCTH1975 cells harbor an activating mutation in EGFR (L858R) and an additional mutation (T790M), which confers resistance to EGFR TKIs including erlotinib and gefitinib. Alpha- gliadin peptide p31-43, gefitinib, and erlotinib were used to treat the cells. Cells were plated at a density of 10,000 cells/well in 24-well cell culture plates and allowed to adhere for 24 hours. The cells were then incubated for 72 hours with the following: (1) vehicle (DMSO/ water); (2) 5 μg/mL, 20 μg/mL, or 70 μg/mL alpha-gliadin peptide p31-43 in DMSO/water; (3) 1 μΜ gefitinib in DMSO/water; (4) 1 μΜ erlotinib in DMSO/water; (5) 5 μg/mL, 20 μg/mL, or 70 μg/mL alpha-gliadin peptide p31-43 and 1 μΜ gefitinib in DMSO/water; or (6) 5 μg/mL, 20 μg/mL, or 70 μg/mL alpha-gliadin peptide p31-43 and 1 μΜ erlotinib in DMSO/water. All experiments were conducted in sextuplicate. For combination therapy using alpha-gliadin peptide p31-43 and gefitinib/erlotinib, the two compounds were administered to the cells simultaneously. Following 72 hours of treatment, growth inhibition was evaluated by the MTT assay according to the manufacturer's instructions. The absorbance at 570 nm was measured using a plate reader. Table 2 shows the mean absorbance at 570 nm and the percent growth inhibition for gliadin- and RTKI-treated NCTH1975 cells compared to vehicle-treated cells.

Table 2: Effects of alpha-gliadin peptide p31-43 alone or in combination with gefitinib or erlotinib on NCI-H1975 cell proliferation following 72-hour treatment

[0059] NCI-H1975 cells treated with alpha-gliadin peptide p31-43 alone exhibited significant growth inhibition compared to control cells. The growth inhibition in cells treated with alpha- gliadin peptide p31-43 alone was greater than in cells treated with gefitinib or erlotinib alone. Treatment with a combination of alpha-gliadin peptide p31-43 and gefitinib or erlotinib achieved significant growth inhibition of the cancer cells at all concentrations tested. Additionally, the combination therapy resulted in increased growth inhibition compared to alpha-gliadin peptide p31-43 or each RTKI alone. As shown in Table 2, co-administration of alpha-gliadin peptide p31-43 and gefitinib or erlotinib surprisingly was able to have a synergistic effect on growth inhibition, with the combination therapy resulting in greater growth inhibition than the sum of the individual growth inhibitory effects of the alpha-gliadin peptide p31-43 and the RTKI.

[0060] Overall, the results demonstrated that a gliadin peptide administered alone was effective at significantly inhibiting the growth of RTKI-resistant cancer cells and achieved greater therapeutic efficacy than a benchmark RTKI. Combination therapy using a gliadin peptide and a RTKI advantageously resulted in significantly increased inhibition of cancer cell growth compared to either the gliadin peptide or RTKI alone and also produced a surprising and unexpected synergistic antitumor effect.

Example 3

[0061] PANC-1 pancreatic carcinoma cells were maintained and cultured as described in

Example 1. Alpha-gliadin peptide p31-43, gefitinib, and erlotinib were used to treat the cells.

Cells were plated at a density of 10,000 cells/well in 24- well cell culture plates and allowed to adhere for 24 hours. The cells were then incubated for 72 hours with the following: (1) vehicle

(DMSO/water); (2) 5 μg/mL, 20 μg/mL, or 70 μg/mL alpha-gliadin peptide p31-43 in

DMSO/water; (3) 1 μΜ gefitinib in DMSO/water; (4) 1 μΜ erlotinib in DMSO/water; (5) 5 μg/mL, 20 μg/mL in DMSO/water, or 70 μg/mL alpha-gliadin peptide p31-43 and 1 μΜ gefitinib in DMSO/water; or (6) 5 μg/mL, 20 μg/mL, or 70 μg/mL alpha-gliadin peptide p31-43 and 1 μΜ erlotinib in DMSO/water. All experiments were conducted in sextuplicate. For combination therapy using alpha-gliadin peptide p31-43 and gefitinib/erlotinib, the two compounds were administered to the cells simultaneously. Following 72 hours of treatment, growth inhibition was evaluated by the MTT assay according to the manufacturer's instructions. The absorbance at 570 nm was measured using a plate reader. Table 3 shows the mean absorbance at 570 nm and the percent growth inhibition for gliadin- and RTKI-treated PANC-1 compared to vehicle-treated cells.

Table 3: Effects of alpha-gliadin peptide p31-43 alone or in combination with gefitinib or erlotinib on PANC-1 cell proliferation following 72-hour treatment

[0062] PANC-1 cells treated with alpha-gliadin peptide p31-43 alone exhibited greater growth inhibition than cells treated with gefitinib or erlotinib alone. Treatment with a combination of alpha-gliadin peptide p31-43 and gefitinib or erlotinib achieved significant growth inhibition of the cancer cells. Additionally, the combination therapy resulted in significantly increased growth inhibition compared to alpha-gliadin peptide p31-43 or each RTKI alone. As shown in Table 3, co-administration of alpha-gliadin peptide p31-43 and gefitinib or erlotinib surprisingly could have a synergistic effect on growth inhibition, with the combination therapy resulting in greater growth inhibition than the sum of the individual growth inhibitory effects of the alpha-gliadin peptide p31-43 and the RTKI.

[0063] Overall, the results demonstrated that a gliadin peptide administered alone was effective at inhibiting the growth of RTKI-resistant cancer cells and achieved greater therapeutic efficacy than a benchmark RTKI. Combination therapy using a gliadin peptide and a RTKI advantageously resulted in significantly increased inhibition of cancer cell growth compared to either the gliadin peptide or RTKI alone and also produced a surprising and unexpected synergistic antitumor effect. Examples 1 to 3 demonstrated that co-administration of a gliadin peptide and a chemotherapeutic agent provided an advantageous therapeutic effect.

Example 4

[0064] PANC-1 human pancreatic carcinoma cells (ATCC) were maintained and cultured as described in Example 1. Alpha-gliadin peptide p31-43 and 5-Fluorouracil (5-FU) (Fisher

Scientific, Pittsburgh, PA) were used to treat the cells. Cells (passage 27) were plated at a density of 1 x 10⁴ cells/well in 24- well cell culture plates and allowed to adhere for 24 hours. Cells were then incubated with vehicle (water) or 5-FU at increasing concentrations for 72 hours. All experiments were conducted in triplicate. After incubation with 5-FU at concentrations ranging from 0 μΜ to 400 μΜ, cells were detached with trypsin and counted. Table 4 shows the mean cell number and percent growth inhibition following treatment with 5-FU.

Table 4: Anti-proliferative effects of 5-FU on PANC-1 cells following 72-hour treatment

[0065] Cells (passage 30) were then plated at a density of 5 x 10³ cells/well in 24- well cell culture plates and allowed to adhere for 24 hours. Cells were incubated with the following: (1) vehicle (DMSO/water); (2) 6.25 μΜ 5-FU; (3) 70 μg/mL alpha-gliadin peptide p31-43; (4) 6.25 μΜ 5-FU and 70 μg/mL alpha-gliadin peptide p31-43 (high combination); or (5) 3.1 μΜ 5-FU and 35 μg/mL alpha-gliadin peptide p31-43 (low combination). All treatments were conducted in triplicate. For combination therapy using alpha-gliadin peptide p31-43 and 5-FU, the two compounds were administered to the cells simultaneously. Media was refreshed with the respective treatments every 72 hours. After 14 days of treatment, cells were trypsinized and counted. Table 5 shows the mean cell number and percent growth inhibition following treatment.

Table 5: Effects of 5-FU alone or in combination with alpha-gliadin peptide p31-43 on PANC-1 cell proliferation following a 14-day treatment regimen

[0066] In order to examine the effects of alpha-gliadin peptide p31-43 on PANC-1 cells exposed to 5-FU for an extended period of time (14 days), an experiment was conducted on the surviving, i.e., resistant, cell population (4%) from the previous experiment. Briefly, after counting viable cells on day 14 of treatment, surviving cells were replated at a density of 5,000 cells per well. The following day, cells were treated with vehicle or 100 μg/mL or 200 μg/mL of alpha-gliadin peptide p31-43. Media containing the respective treatments was refreshed on day 3 and 6. On day 7, cells were trypsinized and counted. Table 6 shows the mean cell number and percent growth inhibition following treatment with alpha-gliadin peptide p31-43.

Table 6: Effects of alpha-gliadin peptide p31-43 on surviving cell population of 5-FU- resistant PANC-1 cells Dose Cell Number/mL % Inhibition

Control 8200 —

100 μg/ml gliadin 3700 55%

200 μg/ml gliadin 1900 77%

[0067] The chemotherapeutic agent 5-FU, which damages DNA, suppressed proliferation of PANC-1 pancreatic cancer cells. The drug inhibited growth of PANC-1 cells by 96% following treatment with 6.25 μΜ for 14 days. Co-administration of 5-FU and a gliadin peptide achieved significant growth inhibition compared to control cells. The results shown in Tables 3 and 5 suggest that the therapeutic efficacy of co-administering a gliadin peptide and a

chemotherapeutic agent compared to either alone could be affected by the site of action (nucleus or cytoplasm) of the chemotherapeutic agent.

[0068] Surprisingly, monotherapy administration of a gliadin peptide alone was effective in killing the cancer cells that prior treatment with 5-FU did not eliminate. Following 5-FU treatment, a surviving population of 5-FU-resistant cells amounting to 4% of the initial population remained viable. When the surviving cell population from 5-FU-treated PANC-1 cells were exposed to alpha-gliadin peptide p31-43 (100 μg/mL or 200 μg/mL) for 7 additional days, cell proliferation was significantly suppressed. The ability of the gliadin peptide to effectively kill cells resistant to a potent chemotherapeutic agent such as 5-FU was surprising and unexpected.

Example 5

[0069] A549 cells were maintained and cultured as described in Example 1. Alpha-gliadin peptide p31-43 and cisplatin (Biovision, Milpitas, CA) were used to treat the cells. Cells (passage 32) were plated at a density of 1 x 10⁴ cells/well in 24- well cell culture plates and allowed to adhere for 24 hours. Cells were then incubated with vehicle (0.9% sodium chloride) or cisplatin at increasing concentrations for 72 hours. All experiments were conducted in triplicate. After incubation with cisplatin at concentrations ranging from 0 μΜ to 6.6 μΜ, cells were detached with trypsin and counted. Table 7 shows the mean cell number and percent growth inhibition following treatment with cisplatin. Table 7: Anti-proliferative effects of cisplatin on A549 cells following 72-hour treatment

[0070] Cells (passage 34) were then plated at a density of 5 x 10³ cells/well in 24- well cell culture plates and allowed to adhere for 24 hours. Cells were incubated with the following: (1) vehicle (DMSO/water); (2) 3.3 μΜ cisplatin; (3) 70 μg/mL alpha-gliadin peptide p31-43; (4) 3.3 μΜ cisplatin and 70 μg/mL alpha-gliadin peptide p31-43 (high combination); or (5) 1.65 μΜ cisplatin and 35 μg/mL alpha-gliadin peptide p31-43 (low combination). All treatments were conducted in triplicate. For combination therapy using alpha-gliadin peptide p31-43 and cisplatin, the two compounds were administered to the cells simultaneously. Media was refreshed with the respective treatments every 72 hours. After 14 days of treatment, cells were trypsinized and counted. Table 8 shows the mean cell number and percent growth inhibition following treatment.

Table 8: Effects of cisplatin alone or in combination with alpha-gliadin peptide p31-43 on A549 cell proliferation following a 14-day treatment regimen

[0071] In order to examine the effects of alpha-gliadin peptide p31-43 on A549 cells exposed to cisplatin for an extended period of time (14 days), a second experiment was conducted on the surviving, i.e., resistant cell population (2%) from the previous experiment. Briefly, after counting viable cells on day 14 of treatment, the surviving cells were replated at a density of 5,000 cells per well. The following day, cells were treated with vehicle or 100 μg/mL or 200 μg/mL of alpha-gliadin peptide p31-43. Media containing the respective treatments was refreshed on day 3 and 6. On day 7, cells were trypsinized and counted. Table 9 shows the mean cell number and growth inhibition following treatment with alpha-gliadin peptide p31-43.

Table 9: Effects of alpha-gliadin peptide p31-43 on surviving cell population of cisplatin- resistant A549 cells

[0072] The chemotherapeutic agent cisplatin, which damages DNA and is characterized as an alkylating agent, suppressed proliferation of A549 lung cancer cells. Cisplatin inhibited proliferation of A549 cells by 98% following treatment with 3.3 μΜ for 14 days. Co-administration of cisplatin and a gliadin peptide achieved significant growth inhibition compared to control cells. The results shown in Tables 3 and 8 suggested that the therapeutic efficacy of co-administering a gliadin peptide and a chemotherapeutic agent compared to either alone could be affected by the site of action (nucleus or cytoplasm) of the chemotherapeutic agent.

[0073] Surprisingly, administration of a gliadin peptide alone was effective in killing the cancer cells that prior treatment with cisplatin did not eliminate. Following cisplatin treatment, a surviving population of cisplatin-resistant cells amounting to 2% of the initial population remained viable. When the surviving cell population from cisplatin-treated A549 cells were exposed to alpha-gliadin peptide p31-43 (100 μg/mL or 200 μg/mL) for 7 additional days, cell proliferation was significantly suppressed. The ability of the gliadin peptide to effectively kill cells resistant to a potent chemotherapeutic agent such as cisplatin was surprising and unexpected.

[0074] Overall, the results in Examples 4 and 5 demonstrated that co-administering a gliadin peptide and a chemotherapeutic agent was effective in significantly inhibiting the growth of cancer cells. Surprisingly, administering a gliadin peptide alone achieved significant suppression of cancer cells that survived prolonged treatment with a potent chemotherapeutic agent. The surprising and unexpected ability of a gliadin peptide to advantageously and effectively kill the most resistant cancer cells, e.g., CSCs, indicated the gliadin peptide could be used in

monotherapy or combination therapy to inhibit tumor growth and prevent cancer relapse.

Administration of a gliadin peptide was therefore effective to decrease or prevent resistance of the cancer to the chemotherapeutic agent.

Example 6

[0075] To determine the phenotype of cells following treatment, A549 cells are treated with 3.3 μΜ cisplatin and PANC-1 cells are treated with 6.25 μΜ 5-FU, with or without alpha-gliadin peptide p31-43, alpha-gliadin peptide p31-49, or alpha-gliadin peptide p31-55 at a concentration from 5 μg/mL to 200 μg/mL, for at least 14 days. Following treatment, Western blot analysis for stem cell markers (CDK12, CycK, OCT4, Nanog, and Sox2) is performed. Treated cells are lysed on ice in lysis buffer. The protein concentration is determined and then the proteins are separated on a 10% TGX polyacrylamide gel and transferred to nitrocellulose membranes. After blocking non-specific proteins, the membranes are incubated with primary antibodies to the stem cell markers or tubulin as a loading control. After being washed, the membranes are incubated for 1 hour with appropriate secondary antibody, and the resulting protein-antibody complexes are detected using enhanced chemiluminescence (ECL) reagent. The Western blot analysis confirms that the cancer cells surviving long-term treatment with a chemotherapeutic express embryonic proteins.

[0076] In one study, A549 cells were incubated with clinically relevant cisplatin

concentrations for several weeks to drive the surviving cells to an embryonic or cancer stem cell phenotype as previously described (Barr et al. PLoS One. 2013; 8(l):e54193). The cells were analyzed for stem cell markers to confirm the identity of the resistant cells effectively treated with a gliadin peptide in Examples 4 and 5. Western blot of the cisplatin treated cells revealed little or no unbound CDK12 and CycK. In contrast, cells treated with alpha-gliadin peptide p31- 43 exhibited markedly more unbound CDK12 and CycK, indicating that the gliadin peptide was competing with CDK12 for binding to CycK and preventing creation of the complex, thereby increasing the sensitivity of the cells to radiation and DNA-damaging chemotherapeutic agents.

Example 7

[0077] The toxicity of alpha-gliadin peptide p31-43 in animals was evaluated. Five- to six- week old female BALB/c mice were dosed with vehicle (100 μΐ_^ DMSO/saline) administered subcutaneously once a day for five days (Group 1) or 200 μg of alpha-gliadin peptide p31-43 in vehicle administered subcutaneously once a day for five days (Group 2). To prepare the gliadin solution, 70 μΐ_^ of sterile DMSO was added to 1 mg of alpha-gliadin peptide p31-43 and vortexed to dissolve the peptide. After the peptide was dissolved, 430 μΐ_^ of sterile 0.9% sodium chloride was added and vortexed to create a 1000 μg/500 μΐ_^ solution of alpha-gliadin peptide p31-43.

[0078] Toxicity was evaluated using daily weight measurements and behavior assessments. The alpha-gliadin peptide p31-43 was associated with no treatment-related deaths. At the end of the study, the mean body weights (+ SE) were 19.8 + 0.4 grams for Group 1 (n=5) and 20.0 + 0.3 grams for Group 2 (n=5). No behavior changes were observed in alpha-gliadin peptide p31-43 treated animals as compared to control mice. Alpha-gliadin peptide p31-43 was therefore tolerated at a dosing level of 10 mg/kg/day without apparent toxicity.

Example 8

[0079] The ability of alpha-gliadin p31-43 to induce apoptosis in cancer cells was assessed. A549 cells were maintained and cultured in RPMI 1640 media containing 10% fetal bovine serum, 2 mM L-glutamine and 1% antibiotic- antimycotic solution. Cells were grown in the presence of 5% C0₂ at 37 °C in an incubator. Induction of apoptosis following treatment with alpha-gliadin peptide p31-43 alone or in combination with gefitinib was determined using the terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL) assay.

[0080] Briefly, A549 cells (1 x 10⁵) were plated in chamber slides and allowed to adhere overnight. The cells were incubated for 72 hours with the following: (1) vehicle control; (2) 1 μΜ gefitinib; (3) 100 μg/mL, 200 μg/mL, or 500 μg/mL alpha-gliadin peptide p31-43; (4) 100 μg/mL, 200 μg/mL, or 500 μg/mL alpha-gliadin peptide p31-43 and 1 μΜ gefitinib. For combination therapy using alpha- gliadin peptide p31-43 and gefitinib, the two compounds were administered to the cells simultaneously. After the 72-hour treatment, the cells were fixed with 4% formaldehyde in PBS (pH 7.4) for 25 minutes at room temperature, then washed twice for 5 minutes in PBS, permeabilized in 0.2% Triton X-100 solution in PBS for 5 minutes at room temperature, and finally washed twice for 5 minutes in PBS. Apoptosis was measured using the DeadEnd™ Colorimetric TUNEL System (Promega, Madison, WI) according to the

manufacturer's instructions. At the end of the assay, the cells were mounted and observed under the microscope. Staining of apoptotic cells was observed for cells treated with alpha-gliadin and/or gefitinib, and the percentage of cells that were apoptotic was determined by counting the number of stained cells within a representative sample. Table 10 shows the percent of cells that were apoptotic following each treatment and the p-value determined using one-way ANOVA analysis of the data for the gliadin- and gefitinib-treated cells compared to the control cells.

Table 10: Effect of gefitinib alone or in combination with alpha-gliadin peptide p31-43 on the induction of apoptosis

[0081] A significantly higher percentage of cells treated with alpha-gliadin peptide p31-43 alone were apoptotic, compared to cells treated with vehicle or gefitinib alone. Additionally, significantly more cells were apoptotic following combination therapy using alpha-gliadin peptide p31-43 and gefitinib, compared to cells treated with vehicle or gefitinib alone. The most effective treatment for inducing apoptosis was the combination of 500 μg/mL alpha-gliadin peptide p31-43 and gefitinib. Overall, the results demonstrated that alpha-gliadin peptide alone or in combination with gefitinib was a potent inducer of apoptosis in human lung cancer cells.

Example 9

[0082] The activity of gefitinib alone or in combination with alpha-gliadin peptide p31-43 was evaluated using an A549 human lung cancer xenograft model. Six- week old female nude mice (Harlan Laboratories, Indianapolis, IN) were quarantined for 3 days and housed 5 mice per cage, with a 12-hour light-dark cycle, and a relative humidity of 50%. Drinking water and diet were supplied to the animals ad libitum. All animals were housed under pathogen-free conditions. On day 4, 5 x 10⁶ A549 cells in 100 of RPMI 1640 media were injected subcutaneously into the right flank of the mice. Starting 24 hours post-inoculation, animals were dosed once daily for 14 days as follows: Group 1 - vehicle (2% DMSO in saline) administered intravenously; Group 2 - 150 mg kg gefitinib administered by gavage; and Group 3 - 150 mg/kg gefitinib administered by gavage and 200 μg alpha-gliadin p31-43 administered intravenously. For combination therapy using alpha- gliadin peptide p31-43 and gefitinib, the two compounds were administered to the cells simultaneously. The animals were monitored for two weeks following the 14-day treatment period. Tumor measurements were initiated as soon as the tumor formed a palpable mass and measured twice weekly. Table 11 shows the mean body weights for the treatment groups over the course of the study.

Table 11: Effect of gefitinib alone or in combination with alpha-gliadin peptide p31-43 on body weight

[0083] All treatments were well tolerated and associated with no drug-related deaths. No significant body weight loss was noted for any of the treatment groups. The mean body weights in grams (± S.E.) at termination were: Group 1 = 22.80 ± 0.88, Group 2 = 22.50 ± 0.44, and Group 3 = 22.92 ± 0.44. Table 12 shows the mean tumor volumes for the treatment groups over the course of the study.

Table 12: Effect of gefitinib alone or in combination with alpha-gliadin peptide p31-43 on tumor volume

[0084] At study termination day (Day 28), mean tumor volumes in cubic millimeters (± S.E.) were: Group 1 = 402.86 ± 95.4, Group 2 = 239.25 ± 32.78, and Group 3 = 145.46 ± 19374. Table 13 shows the mean tumor volumes for the treatment groups over the course of the study.

Table 13: Effect of gefitinib alone or in combination with alpha-gliadin peptide p31-43 on tumor volume

[0085] The percent mean tumor growth inhibition values were 40.6% for Group 2 and 63.9% for Group 3. The tumor doubling times were 17.21 days for Group 1, 24.48 days for Group 2, and 22.89 days for Group 3. The tumor growth inhibition T/C ratio was 57.16 for Group 2 and 44.06 for Group 3.

[0086] Overall, the results demonstrated that combination therapy using gefitinib and a gliadin peptide produced a superior anticancer effect compared to gefitinib alone. The combination therapy was well-tolerated and not toxic to the animals, but was still effective at reducing the tumor burden. The mean tumor volume following combination therapy was reduced by more than 60% compared to control animals. The mean tumor volume was also significantly smaller (about 40%) following combination therapy compared to the mean tumor volume following treatment with gefitinib alone. Additionally, the combination therapy exhibited therapeutic efficacy significantly more rapidly than gefitinib alone, achieving close to 50% tumor growth inhibition within one week and maintaining greater than 60% growth inhibition for two weeks following cessation of treatment.

Example 10

[0087] Cancer cells of various types including NSCLC (A549) and PANC-1 are obtained from American Type Culture Collection (ATCC; Manassas, VA) or biopsies from cancer patients and maintained in growth medium. Cells are plated in multi-well cell culture plates and exposed to a single dose of radiation at a strength between 0 Gy (control) and 20 Gy using an x-ray irradiator (Faxitron Bioptics; Tucson, AZ) or mock-irradiated as a control. Before, during, or after irradiation, cells are treated in the following experimental groups: (1) cells incubated with growth medium only; (2) cells incubated with growth medium supplemented with multiple concentrations of alpha-gliadin peptide p31-43, alpha-gliadin peptide p31-49, or alpha-gliadin peptide p31-55 at a concentration from 5 μg/mL to 200 μg/mL; (3) cells incubated with growth medium supplemented with multiple concentrations of erlotinib from 0.1 uM to 10 uM; (4) cells incubated with growth medium supplemented with 5 μg/mL to 200 μg/mL alpha-gliadin peptide p31-43, alpha-gliadin peptide p31-49, or alpha-gliadin peptide p31-55 and 0.1 μΜ to 10 μΜ erlotinib; (5) cells incubated with growth medium supplemented with multiple concentrations of gefitinib from 0.1 μΜ to 10 μΜ; and (6) cells incubated with growth medium supplemented with 5 μg/mL to 200 μg/mL alpha-gliadin peptide p31-43, alpha-gliadin peptide p31-49, or alpha- gliadin peptide p31-55 and 0.1 μΜ to 10 μΜ gefitinib. In one study, A549 and PANC-1 cells are irradiated with a 10 Gy dose of irradiation and then treated 24 hours post irradiation with gefitinib (1 μΜ) alone or gefitinib in combination with alpha-gliadin peptide p31-43, alpha- gliadin peptide p31-49, or alpha-gliadin peptide p31-55, for at least 1 day.

[0088] During treatment, the concentration of alpha-gliadin peptide in the growth medium is measured using enzyme-linked immunosorbent assay (ELISA) with an anti-gliadin antibody (RIDASCREEN Gliadin; R. Biopharm, Inc.; Germany) to measure the uptake of the alpha- gliadin peptide into the cells. Following treatment, cells are washed twice with phosphate- buffered saline before being incubated with fresh drug-free medium. Cell colonies are then fixed, stained (0.5% [w/v] crystal violet in 5% acetic acid, 20% H₂0, 75% methanol) and counted. Cell viability is measured after 7 to 14 days and the half-maximal inhibitor

concentration (IC₅₀) of erlotinib or gefitinib or combination therapy is determined from the dose- response curve. Administering radiation and a gliadin peptide results in increased cytotoxicity compared to radiation alone. Administration of a gliadin peptide and erlotinib significantly decreases the IC₅₀ of erlotinib compared to the IC₅₀ for erlotinib administered alone. Similarly, administration of a gliadin peptide and gefitinib significantly decreases the IC₅₀ of gefitinib compared to the IC₅₀ of gefitinib administered alone. Administration of radiation, a gliadin peptide, and erlotinib or gefitinib results in the most significant decrease in cell viability compared to control cells receiving no anticancer therapy.

[0089] Western blot analysis for stem cell markers (CDK12, CycK, OCT4, Nanog, and Sox2) is performed to evaluate the phenotype of the treated cells as described in Example 6. Cells treated with alpha-gliadin peptide p31-43, alpha-gliadin peptide p31-49, or alpha-gliadin peptide p31-55 exhibit higher levels of the stem cell markers compared to cells treated with irradiation or erlotinib/gefitinib alone, indicating that treatment with a gliadin peptide promotes an embryonic phenotype, thereby increasing the sensitivity of the cells to radiation and DNA-damaging chemotherapeutic agents.

Example 11 [0090] Mice are injected subcutaneously with cancer cells, e.g., NSCLC cells, in the flank region. Tumors are allowed to grow to about 100 cubic millimeters to 200 cubic millimeters. Animals receive a single dose of radiation at a strength between 0 Gy (control) and 20 Gy, or multiple lower-doses between 0 Gy and 5 Gy spaced one or more days apart. Before, during, or after irradiation, the animals are treated in the following experimental groups for 14 days: (1) animals receiving a once daily saline injection into the tumor site; (2) animals receiving a once daily injection of 5 μg/mL to 200 μg/mL of alpha-gliadin peptide p31-43, alpha-gliadin peptide p31-49, or alpha-gliadin peptide p31-55 into the tumor site; (3) animals receiving a once daily oral dose of up to 100 mg/kg erlotinib; (4) animals receiving a once daily oral dose of up to 100 mg/kg gefitinib; (5) animals receiving a once daily injection of 5 μg/mL to 200 μg/mL of alpha- gliadin peptide p31-43, alpha-gliadin peptide p31-49, or alpha-gliadin peptide p31-55 into the tumor site and once daily oral dose of up to 100 mg/kg erlotinib; (6) animals receiving a once daily injection of 5 μg/mL to 200 μg/mL alpha-gliadin peptide p31-43, alpha-gliadin peptide p31-49, or alpha-gliadin peptide p31-55 into the tumor site and once daily oral dose of up to 100 mg/kg gefitinib.

[0091] The plasma concentration of the alpha-gliadin peptide in the animals is measured before and at multiple time points following treatment to determine the clearance of the alpha- gliadin peptide in vivo. Plasma samples are obtained from the animals and the concentration of the alpha-gliadin peptide is measured using ELISA with an anti-gliadin antibody. The concentration of the alpha-gliadin peptide in tissue and organ samples following treatment is also measured using ELISA to determine the distribution of the alpha-gliadin peptide.

[0092] Tumor volumes are evaluated using calipers over the course of treatment to determine growth inhibition. Administering radiation and a gliadin peptide results in a greater decrease in tumor size compared to radiation alone. Administration of a gliadin peptide and erlotinib or gefitinib significantly decreases tumor volumes compared to erlotinib or gefitinib administered alone. Administration of radiation, a gliadin peptide, and erlotinib or gefitinib results in the most significant decrease in tumor volumes compared to control animals receiving no anticancer therapy.

Example 12 [0093] The activity of alpha-gliadin peptide p31-43, radiation, and gefitinib, alone or in combination, is evaluated using an A549 human lung cancer xenograft model. Fifty- five athymic nude female mice (3- to 4-weeks old) are purchased from Harlan Laboratories (Indianapolis, IN) and quarantined for 5 days. At Day 1 post-quarantine, animals are injected subcutaneously with 1.5 x 10⁶ A549 cells per mouse at a single site. The animals are randomized into either control or treatment groups (5 animals per group) and treated for 14 days according to the schedule in Table 14.

Table 14: Treatment schedule for alpha-gliadin peptide p31-43, gefitinib, and radiation

Days 7-9

[0094] Control animals (Groups 1-4) receive treatment with a single agent (i.e., alpha-gliadin peptide p31-43, gefitinib, or radiation). Mice in Groups 1, 2, 5, and 7-11 receive either 200 μg or 500 μg daily of alpha-gliadin peptide p31-43 administered intravenously on Days 1-14. Mice in Groups 3, 6-8, 10, and 11 receive 50 mg/kg gefitinib daily administered by gavage on Days 1-3 (Groups 3 and 6) or Days 7-9 (Groups 7, 8, 10 and 11). Mice in Groups 4 and 6 receive radiation on Day 1, and mice in Groups 5, 8, 9 and 11 receive radiation on Day 7, using a Faxitron® (Tuscon, AZ) RX650 irradiator. During radiotherapy, mice are placed in a Plexiglass cage at a distance of about 16 inches from the X-ray tube and irradiated with a total dose of 10 Gy over a period of 5.5 minutes with approximately 1.82 Gy/min. The animals are allowed to recover for 24 hours before receiving a dose of alpha-gliadin peptide p31-43 and/or gefitinib.

[0095] The body weight of the animals is measured prior to the first treatment and then every 2 days until the end of the study. The general health and behavior (e.g., signs of morbidity, mortality, feeding, grooming, etc.) are monitored daily to the end of the study. Tumor size is assessed using caliper measurement (i.e., shortest diameter (W) and longest diameter (L), measured with vernier caliper), and tumor volume is calculated using the formula 0.52 x L x W , starting as soon as a tumor is visible and continuing biweekly until the end of the study. The study duration is 6 to 8 weeks depending on the rate of tumor growth, and animals are sacrificed at the end of the study. Animals with tumors of > 2,000 mm are sacrificed prior to the end of the study as needed. At the time of sacrifice, animals are weighed, and tumors are measured. Adverse effects on tissue relating to radiation are recorded.

[0096] Administration of a gliadin peptide followed by radiation results in a greater decrease in tumor size compared to radiation or a gliadin peptide administered alone. Administration of a gliadin peptide followed by administration of gefitinib significantly decreases tumor volumes compared to a gliadin peptide or gefitinib administered alone. Administration of a gliadin peptide followed by gefitinib and radiation results in the most significant decrease in tumor volumes compared to control animals. Combination therapy comprising a gliadin peptide and radiation, or a gliadin peptide, radiation, and gefitinib, is well-tolerated, but still effective at reducing tumor burden.

Example 13

[0097] An efficacy study in humans is conducted to evaluate the effect of co-administration of (1) -gliadin peptide p31-43, alpha-gliadin peptide p31-49, or alpha-gliadin peptide p31-55; (2) alpha-gliadin peptide p31-43, alpha-gliadin peptide p31-49, or alpha-gliadin peptide p31-55 and gefitinib; or (3) alpha-gliadin peptide p31-43, alpha-gliadin peptide p31-49, or alpha-gliadin peptide p31-55 and erlotinib in patients with NSCLC before, during, or after receiving radiotherapy. Patients receive radiotherapy according to the standard of care for the patient's condition. Patients are administered alpha-gliadin peptide p31-43, alpha-gliadin peptide p31-49, or alpha-gliadin peptide p31-55 daily to achieve a plasma concentration of about 5 μg/mL to about 200 μg/mL. Patients also receiving a RTKI are dosed with up to 250 mg daily of gefitinib or up to 150 mg daily of erlotinib. Tumor mass and metastasis are evaluated after one, two, three, and six months of therapy. Patients receiving a gliadin peptide in addition to radiation exhibit a significantly reduced primary tumor mass in the lungs and fewer metastatic tumors compared to patients receiving a radiation alone. Patients receiving a gliadin peptide and a RTKI exhibit a significantly reduced primary tumor mass in the lungs and fewer metastatic tumors compared to patients receiving a RTKI alone. Patients receiving radiation, a gliadin peptide, and erlotinib or gefitinib exhibit the greatest reduction in primary tumor mass in the lungs compared to control animals receiving no anticancer therapy. The clinical trial demonstrates the value of including administration of a gliadin peptide, radiation therapy, and optionally a RTKI to treat cancer.

[0098] The foregoing Examples are provided to further illustrate the invention without being limiting. While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the claims all such changes and modifications that are within the scope of this invention.

Claims

What is Claimed:

1. A method of treating cancer comprising administering a therapeutically effective regimen comprising administering a gliadin peptide and radiation therapy to a patient with cancer.

2. Use of a therapeutically effective regimen comprising administering a gliadin peptide and radiation therapy to treat cancer in a patient.

3. The method or use of claim 1 or claim 2, wherein the gliadin peptide is administered in an amount effective to decrease the radioresistance and/or increase the radiosensitivity of the cancer.

4. The method or use of any of claims 1-3, wherein the therapeutically effective regimen further comprises administering at least one chemotherapeutic agent.

5. The method or use of claim 4, wherein the gliadin peptide and radiation therapy are administered in an amount effective to decrease the chemoresistance and/or increase the chemosensitivity of the cancer to the chemotherapeutic agent.

6. The method or use of claim 4 or claim 5, wherein the gliadin peptide and radiation therapy are administered in an amount effective to increase the efficacy of the chemotherapeutic agent.

7. A method of treating cancer comprising administering a therapeutically effective regimen comprising administering a gliadin peptide, radiation therapy, and at least one chemotherapeutic agent to a patient with cancer.

8. Use of a therapeutically effective regimen comprising administering a gliadin peptide, radiation therapy, and at least one chemotherapeutic agent to treat cancer in a patient.

9. The method or use of any of claims 4-8, wherein the chemotherapeutic agent is selected from the group consisting of alkylating agents, antibiotics, antimetabolites, differentiating agents, mitotic inhibitors, steroids, topoisomerase inhibitors, tyrosine kinase inhibitors, and combinations thereof.

10. The method or use of any of claims 4-9, wherein the chemotherapeutic agent is selected from the group consisting of azacitidine, axathioprine, bevacizumab, bleomycin, capecitabine, carboplatin, chlorabucil, cisplatin, cyclophosphamide, cytarabine, daunorubicin, docetaxel, doxifluridine, doxorubicin, epirubicin, etoposide, fluorouracil, gemcitabine, herceptin, idarubicin, mechlorethamine, melphalan, mercaptopurine, methotrexate, mitoxantrone, oxaliplatin, paclitaxel, tafluposide, teniposide, tioguanine, retinoic acid, valrubicin, vinblastine, vincristine, vindesine, vinorelbine, and combinations thereof.

11. The method or use of any of claims 4-9, wherein the chemotherapeutic agent is a receptor tyrosine kinase inhibitor.

12. The method or use of claim 11, wherein the receptor tyrosine kinase inhibitor is an epidermal growth factor receptor (EGFR) inhibitor.

13. The method or use of claim 12, wherein the EGFR inhibitor is gefitinib.

14. The method or use of claim 12, wherein the EGFR inhibitor is erlotinib.

15. The method or use of any of claims 4-14, wherein the chemotherapeutic agent and the gliadin peptide are co-administered.

16. The method or use of any of claims 4-15, wherein the chemotherapeutic agent is administered before the gliadin peptide is administered.

17. The method or use of any of claims 4-15, wherein the chemotherapeutic agent is administered after the gliadin peptide is administered.

18. The method or use of any of claims 4-15, wherein the chemo therapeutic agent and gliadin peptide are administered concurrently.

19. The method or use of any of claims 4-18, wherein the chemo therapeutic agent and radiation therapy are co-administered.

20. The method or use of any of claims 4-19, wherein the chemotherapeutic agent is administered before the radiation therapy is administered.

21. The method or use of any of claims 4-19, wherein the chemotherapeutic agent is administered after the radiation therapy is administered.

22. The method or use of any of claims 4-19, wherein the chemotherapeutic agent and radiation therapy are administered concurrently.

23. A method of increasing tumor radiosensitivity and/or decreasing tumor radioresistance comprising administering a therapeutically effective amount of a gliadin peptide to a patient with cancer.

24. Use of a therapeutically effective amount of a gliadin peptide to increase tumor radiosensitivity and/or decrease tumor radioresistance in a patient with cancer.

25. The method or use of claim 23 or claim 24, further comprising administering radiation therapy to the patient.

26. The method or use of any of claims 1-22 or 25, wherein the gliadin peptide and radiation therapy are co-administered.

27. The method or use of any of claims 1-22 or 25-26, wherein the gliadin peptide is administered before the radiation therapy is administered.

28. The method or use of any of claims 1-22 or 25-26, wherein the gliadin peptide is administered after the radiation therapy is administered.

29. The method or use of any of claims 1-22 or 25-26, wherein the gliadin peptide and the radiation therapy are administered concurrently.

30. A method of killing a chemoresistant and/or radioresistant cancer cell comprising administering an effective amount of a gliadin peptide to a patient having cancer.

31. Use of a therapeutically effective amount of a gliadin peptide to kill a chemoresistant and/or radioresistance cancer cell.

32. The method or use of claim 30 or 31, wherein the patient previously received radiotherapy and/or chemotherapy.

33. The method or use of any of claims 30-32, wherein the chemoresistant and/or radioresistant cancer cell is a cancer stem cell.

34. The method or use of any of claims 1-33, wherein the gliadin peptide is an alpha- gliadin peptide or a derivative or fragment thereof.

35. The method of any of claims 1-34, wherein the gliadin peptide comprises at least alpha-gliadin peptide p31-55.

36. The method or use of any of claims 1-35, wherein the alpha-gliadin peptide comprises at least alpha-gliadin peptide p31-43.

37. The method or use of any of claims 1-36, wherein the gliadin peptide is an alpha- gliadin peptide selected from the group consisting of alpha-gliadin peptide p31-55, alpha-gliadin peptide p31-49, alpha-gliadin peptide p31-43 and derivatives and fragments thereof.

38. The method or use of any of claims 1-37, wherein the gliadin peptide comprises or a derivative or fragment thereof.

39. The method or use of any of claims 1-38, wherein the gliadin peptide comprises SEQ ID NO: 1 or a derivative or fragment thereof.

40. The method or use of any of claims 1-39, wherein the gliadin peptide comprises SEQ ID NO:2 or a derivative or fragment thereof.

41. The method or use of any of claims 1-40, wherein the gliadin peptide comprises SEQ ID NO:3 or a derivative or fragment thereof.

42. The method or use of any of claims 1-41, wherein the gliadin peptide is administered parenterally.

43. The method or use of any of claims 1-42, wherein the patient is human.

44. The method or use of any of claims 1-43, wherein the patient has previously had cancer resection surgery.

45. The method or use of any of claims 1-44, wherein the cancer is selected from the group consisting of bladder cancer, breast cancer, colon cancer, endometrial cancer, kidney cancer, leukemia, lung cancer, lymphoma, pancreatic cancer, prostate cancer, skin cancer, brain cancer, thyroid cancer, and metastatic forms thereof.

46. The method or use of any of claims 1-45, wherein the cancer is non- small cell lung cancer.

47. The method or use of any of claims 1-46, wherein the patient does not have mutations in the EGFR gene known to increase radiosensitivity and/or chemosensitivity to EGFR inhibitors.